Rotary drum for waste incinerator

ABSTRACT

A rotary drum for waste incinerator, of the type having an outer casing, a coaxial gas-pervious support for a waste, longitudinal partitions between the casing and the support and apertures in the casing for admitting air or for exhausting fumes, said apertures opening in ducts laterally bounded by the lateral partitions. A transverse partition, located between the casing and the gaspervious support, divides each one of the ducts in a section in which flows the admitted air and a section in which flow the fumes to be exhausted.

States Patent Inventors Paul Lerner Montrouge; Georges Poterlot, Pont Sainte Maxence, both of, France Appl. No 16,652

Filed Mar. 5. 1970 Patented June 15,1971

Assignee La Soudure Autogene F rancaise Paris, France Priority Mar. 31, 1969 France 6909647 ROTARY DRUM FOR WASTE INCINERATOR 5 Claims, 3 Drawing Figs.

U.S. Cl 1 10/14 Int. Cl F23g 5/06 Field ofSearch 110/14, 15;

[56] References Cited UNITED STATES PATENTS 1,583,436 5/1926 Atkinson 110/14 3,152,796 10/1964 Ramstack, Jr. 110/14 FOREIGN PATENTS 1,445,141 '5/1966 France 1. 110/14 1,494,262 7/1967 France 110/14 Primary Examiner- Kenneth W. Sprague Altorney- Young and Thompson ABSTRACT: A rotary drum for waste incinerator, of the type having an outer casing. a coaxial gas-pervious support for a waste, longitudinal partitions between the casing and the support and apertures in the casing for admitting air or for exhausting fumes, said apertures opening in ducts laterally bounded by the lateral partitions.

A transverse partition, located between the casing and the gas-pervious support, divides each one of the ducts in a section in which flows the admitted air and a section in which flow the fumes to be exhausted.

PATENTED JUN} 5 :97:

baa mum:

WW L 7 e T e a d Q M Z7 60 ROTARY DRUM FOR WASTE INCINERATOR This invention relates to rotary drum waste incinerators and more particularly is concerned with continuously operable rotary drum waste incinerators.

Rotary dl'ul'll waste incinerators are known; see, for example, French Pat. No. 1,421,532. A common disadvantage of these known incinerators is that the support for the waste material in certain places is in contact with the hottest of the waste material and has the hot spent gases passing through it. In such places, it is necessary to use expensive heat-resistant steels.

According to the present invention there is provided a rotary drum waste incinerator, which can operate continuously and which comprises (a) a drum, including an outer casing and a longitudinally extending gas-permeable support within and spaced from said outer casing for supporting the material to be incinerated, said drum, in operation, being rotated about a substantially horizontal axis within said longitudinally extending gas-permeable support, (b) means for supplying waste material to be incinerated to one end of said longitudinally extending gas-permeable support, (c) a first means for conducting air, or other gas capable of supporting the combustion of the material to be incinerated, to the longitudinally extending gas permeable support, (d) a second means for conducting spent gases away from said longitudinally extending gaspermeable support to the exterior of the drum, and (e) gas-impermeable third means separating said first and second means, wherein:

i. said outer casing is constructed from a material which is nonpermeable to gases;

ii. Those parts of said first means which are closest to the axis of rotation of the drum are further away from said means for supplying waste material to one end of said longitudinally extending gas-permeable support than are those parts of said second means which are closest to the axis of rotation of the drum;

iii. said first means comprises a number of openings in said outer casing and a number of partitions extendingintothe gap between said outer casing and said longitudinally extending gas-permeable support so as to form channels directing the air, or other gas capable of supporting the combustion of the material to be incinerated, from said openings to said longitudinally extending gas-permeable support; and

iv. said second means comprises a number of openings in said outer casing and a number of partitions extending into the gap between said outer casing and said longitudinally extending gas-permeable support so as to form channels directing spent gases away from said longitudinally extending gaspermeable support to said openings.

Advantageously, the longitudinally extending gas-permeable support is cylindrical. The first and second means preferably comprise longitudinally extending partitions extending from and connecting the outer casing to the longitudinally extending gas-permeable support, thereby forming ducts therebetween. These can be linear and can be parallel to the axis of rotation ofthe drum. The openings in the outer casing comprising said first and second means are advantageously positioned between each adjacent pair of partitions.

Preferably, devices are provided in said first and second means which limit the number of pathways available to the gases passing through said first and second means; more preferably, said first means is provided with means for hindering the access of, for example, air to those openingswhich, at any given time, communicate with the upper surface of the gas-permeable support. Similarly, said second means is more preferably provided with means for hindering the outlet of spent gases from those openings which do not, at any given time, communicate with the upper surface of the gas-permeable support; this is most preferable when a means for extracting spent gases from the rotary drum waste incinerator (for example, an extractor fan) is used in conjunction with the rotary drum waste incinerator. The design and exact location of these hindering means of said first and second means will depend, to a certain extent, on the direction of rotation of the rotary drum waste incinerator, and the capacity at which it is expected to work, since it is desirable to have all the incoming gas or gases pass through the waste material which is being incinerated, and also since it is desirable to have the hot spent gases in contact with the surface of the heap of the incoming waste material which is to be incinerated while at the same time avoiding that the smallest particles of the incoming waste material pass out of the gas-permeable cylinder with the spent gases. This latter effect would be particularly hazardous if, for example, the suction produced by an extractor fan were allowed to reach those openings in the outer casing which, at any given time, communicate with the area of the gas-permeable support which is supporting the waste material.

The third means can advantageously be a partition extending across the channels around the circumference of the gaspermeable support and connecting it to the outer casing.

The outer casing can be capped by a front end plate which does not rotate; such an end plate can advantageously form part of the means for supplying waste material to the gas permeable support. A device at the disposal end of the rotary drum waste incinerator can be provided to facilitate, or direct, the issue of burnt material therefrom. One of said plates may be provided with a burner for kindling the waste materials when the operation ofthe incinerator is being started.

The rotary drum waste incinerator can be constructed of easily removable sections; thus when one section needs replacing the operation can easily be performed.

A rotary drum waste incinerator according to the present invention can be used for the incineration of many different kinds of waste material, and more particularly for the incineration of household refuse.

A rotary drum waste incinerator according to the present invention has the advantage that the air, or other gas capable of supporting the combustion of the material to be incinerated, is introduced into the bed of waste material only when the waste material has already been substantially dried.

In a preferred embodiment of the present invention the rotary drum waste incinerator comprises (a) a drum, including an outer casing and a gas-permeable cylindrical support within and spaced from said outer casing for supporting the material to be incinerated, said drum, in operation, being rotated about the substantially horizontal axis of said gas-permeable cylindrical support; (b) means for supplying waste material to be incinerated to one end of said gas-permeable cylindrical support; (d) a second means for conducting spent gases from the gas-permeable cylindrical support to the exterior of the drum; and (e) a transverse partition extending around the circumference of the gas-permeable cylindrical support between the gas-permeable cylindrical support and the outer casing separating said first and second means; wherein:

i. said outer casing is constructed from a material which is nonpermeable to gases;

ii. those parts of said first means which are closest to the axis of rotation of the drum are further away from said means for supplying waste material to one end of said gas-permeable cylindrical support than are those parts of said second means which are closest to the axis of rotation of the drum; iii. said first means for conducting air, other gas capable of supporting the combustion of the material to be incinerated, to the gaspermeable cylindrical support comprises a number of partitions parallel to the axis of rotation of the drum and extending radially between the outer casing and the gas-permeable cylindrical support so as to form ducts therebetween, openings in the outer casing between each adjacent pair of said partitions,

and means for preventing the entry of air, or other gas capable of supporting the combustion of the material to be incinerated, to all ducts except those which, during operation of the incinerator, lie beneath the waste material held on the gaspermeable cylindrical support;

iv. said second means for conducting spent gases from the gas-permeable cylindrical support to the exterior of the drum comprises a number of partitions parallel to the axis of rotation of the drum and extending radially between the outer casing and the gas-permeable cylindrical support so as to form ducts therebetween, openings in the outer casing between each adjacent pair of said partitions, and means for preventing the escape of spent gases from all ducts except those which, during operation of the incinerator, are above the waste material held on the gas-permeable cylindrical support; and

v. said transverse partition is closer to the means for supplying waste material to the drum than is the midpoint of the gaspermeable cylindrical support. For a better understanding of the invention, and to show how the same can be carried into effect, reference will now be made, by way of example, to the accompanying drawing, in which:

FIG. 1 is a vertical sectional view through the axis of a rotary drum waste incinerator according to the present invention;

FIG. 2 is across section taken on the line II-II of FIG. I; and

FIG. 3 is a cross section taken on the line III-III of FIG. 1. In FIG. I, the incinerator is assumed to be empty of waste. Its drum includes an outer casing 2 which is nonpermeable to gases and a gas-permeable cylindrical support 4 for holding the waste material to be incinerated. A number oflongitudinal partitions, which are parallel to the axis of rotation of the drum, connect the outer casing to the gas-permeable cylindrical support. In operation, the drum rotates about the horizontal axis 6-6.

FIG. 2 shows the means for conducting spent gases away from the gas-permeable cylindrical support and FIG. 3 shows the means for supplying the combustion-supporting gas to the gas-permeable cylindrical support. FIG. 2 shows twelve openings such as 8', 10 which provide an outlet for spent gases through the outer casing 2, and FIG. 3 shows twelve openings such as 12, 14 which provide an inlet for air, or other gas capable of supporting the combustion of the material to be incinerated, into the outer casing 2. In both FIG. 2 and FIG. 3, twelve partitions, such as l6, I7, 18, connect the outer casing 2 to the gas-permeable cylindrical support 4 and form therewith ducts such as 20, 22. The openings, such as 8, l0, 12, 14, allow gases to pass through the ducts. As FIG. 2 shows, a nonrotating casing 34 surrounds the outer casing 2 and comprises internally, along its entire length and parallel to the axis of the drum, a small flange 36 and a cover 38; these limit the action of the suction produced at the outlet of the casing 34 (by a fan or by chimney for example) to those of the ducts which are situated above the heap of waste material 40 to be incinerated. The air, or other gas capable of supporting the combustion of the material to be incinerated, enters the incinerator through a casing 44, illustrated in FIG. 3, which is nonrotating and surrounds the outer casing 3. This casing 44 comprises a small flange 46 and a cover 48, these only allow air to enter the drum through the holes in the gas-permeable cylindrical support 4 which are situated below the heap of waste material 40 being incinerated.

A transverse partition 50 extends between the outer casing 2 and the gas-permeable cylindrical support 4 and separates the means for conducting spent gases away from the gaspermeable cylindrical support from the means for conducting a combustion-promoting gas to the gas-permeable cylindrical support. Good results are obtained when the transverse partition is separated from the supply-end of the gas-permeable cylindrical support by a distance in the range from 0.2 to 0.5 times the length of the gas-permeable cylindrical support.

The outer casing 2 is very near the inner edges of the casings 34 and 44 but does not touch them. It is supported by wheels not shown in the drawings and is rotated by one of these wheels or by a gear rim.

The drum is capped by a front plate 24 and a rear device 26. The front plate forms part ofa charging device 28, which has a piston 30 and a supply hopper 32. The rear device comprises a channel 42 into which material is discharged when it leans the ri ht-hand end of the drum.

n the embodiment illustrated, the portion of the drum nearest to the charging device can be filled to approximately one third capacity, while allowing spent gases to pass out through five or six ducts of FIG. 2 and air to enter through three or four ducts of FIG. 3.

When the incinerator is in operation, air passes into the casing 44, enters the ducts at the right hand side of partition 50 and passes through the gas-permeable cylindrical support 4. The temperature of the gas-permeable cylindrical support remains fairly moderate since it is cooled by this incoming air. The air then passes through the waste material and supports its combustion. The waste material becomes more completely incinerated as it moved towards the rear plate of the drum. After oxidizing the waste material, the spent gases flow towards the front plate of the drum and escape through the gas-permeable cylindrical support 4 into ducts within casing 34 and thence to a chimney or other means of disposal. Before passing through the support, the spent gases pass over the heap of waste material which is continually agitated by the drum rotation. Thus they preheat and dry the waste material to a considerable extent before it enters the combustion zone.

Preheating is also provided by contact of the waste material with the gas-permeable cylindrical support 4, since the latter is heated by the spent gases during the time in which they come into contact with it during the rotation of the drum. The contact with the waste material cools the gas-permeable cylindrical support 4, which avoids overheating the latter.

What we claim is:

1, In a waste incinerator comprising a drum adapted to continuously rotate about its axis, said drum comprising an external envelope impervious to gas and an internal gas-pervious support for the waste to be incinerated, a plurality of longitudinal partitions between and fixed to the envelope and the support and forming longitudinal duets with the envelope and the support, means to feed waste to be incinerated into one end of the support and means for removing incinerated waste from the other end of the support; the improvement comprising transverse partitions dividing said ducts into sections adjacent said one end and sections adjacent said other end, means to connect said sections adjacent one end with and to mask said sections adjacent one end from a combustion gas discharge depending on their position due to rotation of the drum, and means to connect said sections adjacent the other end with and to mask said sections adjacent the other end from communication with a source of combustion-supporting gas depending on their position due to rotation of the drum.

2. Apparatus as claimed in claim I, said partitions being disposed between a fifth and a half of the length of the ducts from said one end.

3. Apparatus as claimed in claim 1, there being first openings through said envelope between said longitudinal partitions communicating between said sections adjacent said one end and said combustion gas discharge, and second openings through said envelope between said longitudinal partitions communicating between said sections adjacent said other end and said source of combustion-supporting gas.

4. Apparatus as claimed in claim 3, said masking means comprising means exposing said first openings on the upper side of the drum and masking said first openings on the under side of the drum, and exposing said second openings on the under side of the drum and masking said second openings on the upper side of the drum whereby combustion-supporting gas enters the under side of the drum and combustion gas leaves the upper side of the drum.

5. Apparatus as claimed in claim 1, said ducts being closed at their ends. 

1. In a waste incinerator comprising a drum adapted to continuously rotate about its axis, said drum comprising an external envelope impervious to gas and an internal gas-pervious support for the waste to be incinerated, a plurality of longitudinal partitions between and fixed to the envelope and the support and forming longitudinal ducts with the envelope and the support, means to feed waste to be incinerated into one end of the support and means for removing incinerated waste from the other end of the support; the improvement comprising transverse partitions dividing said ducts into sections adjacent said one end and sections adjacent said other end, means to connect said sections adjacenT one end with and to mask said sections adjacent one end from a combustion gas discharge depending on their position due to rotation of the drum, and means to connect said sections adjacent the other end with and to mask said sections adjacent the other end from communication with a source of combustion-supporting gas depending on their position due to rotation of the drum.
 2. Apparatus as claimed in claim 1, said partitions being disposed between a fifth and a half of the length of the ducts from said one end.
 3. Apparatus as claimed in claim 1, there being first openings through said envelope between said longitudinal partitions communicating between said sections adjacent said one end and said combustion gas discharge, and second openings through said envelope between said longitudinal partitions communicating between said sections adjacent said other end and said source of combustion-supporting gas.
 4. Apparatus as claimed in claim 3, said masking means comprising means exposing said first openings on the upper side of the drum and masking said first openings on the under side of the drum, and exposing said second openings on the under side of the drum and masking said second openings on the upper side of the drum whereby combustion-supporting gas enters the under side of the drum and combustion gas leaves the upper side of the drum.
 5. Apparatus as claimed in claim 1, said ducts being closed at their ends. 